A server-side request forgery vulnerability and remote port scanning using pingbacks. This vulnerability, which could potentially be used to expose information and compromise a site, affects all previous WordPress versions. This was fixed by the WordPress security team. We’d like to thank security researchers Gennady Kovshenin and Ryan Dewhurst for reviewing our work.

Two instances of cross-site scripting via shortcodes and post content. These issues were discovered by Jon Cave of the WordPress security team.

A cross-site scripting vulnerability in the external library Plupload. Thanks to the Moxiecode team for working with us on this, and for releasing Plupload 1.5.5 to address this issue.

The first security issue is one we talked about a few weeks ago. We were surprised it wasn’t addressed in version 3.5, but it does appear to be fixed now.

The other two are – as it says – cross-site scripting vulnerabilities, which are responsible for nearly all of the security issues online today. According to Wikipedia:

Cross-site scripting (XSS) is a type of computer security vulnerability typically found in Web applications. Due to breaches of browser security, XSS enables attackers to inject client-side script into Web pages viewed by other users. A cross-site scripting vulnerability may be used by attackers to bypass access controls such as the same origin policy. Cross-site scripting carried out on websites accounted for roughly 84% of all security vulnerabilities documented by Symantec as of 2007.[1] Their effect may range from a petty nuisance to a significant security risk, depending on the sensitivity of the data handled by the vulnerable site and the nature of any security mitigation implemented by the site’s owner.

Since this is not a major release but rather a maintenance and security update you won’t find any new features inside, and the potential for conflicts in your themes and plugins is also greatly reduced. It is critical that you update your sites, however.

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